The City Council and Bloomberg administration officials will announce stepped-up rules today targeting landlords who neglect bedbug problems in their buildings.

Under the new rules — which take effect immediately — building owners must inspect and treat apartments next to, above and below any unit that has bedbugs. They also must notify all tenants when bedbugs have been detected and distribute a plan on eradicating them.

Property owners who repeatedly fail to take care of bedbug infestations will be required to get a licensed exterminator to fill out a sworn affidavit indicating the problem has been handled.

“We’re sending the message that we’re taking this seriously,” Council Speaker Christine Quinn said. “People are very nervous about bedbugs.”

The Department of Health will be empowered to send landlords who ignore bedbugs to the city’s Environmental Control Board, which can issue fines. Presently, only the Department of Housing Preservation and Development can issue violations to landlords for bedbugs.

In a last-resort move, the city would sell liens on properties whose owners ignore those fines.

The Web site will provide pictures and detailed descriptions of the critters and tips on how to prevent them from entering homes, such as keeping suitcases off floors and beds while traveling, sealing cracks in your home with caulk and washing clothes and bedding on hot settings if you suspect the presence of bedbugs.

The site also advises against bringing home any used furniture off the street.

Councilwoman Gale Brewer (D-Manhattan), who worked on the Web site and new regulations, said many New Yorkers are in a constant state of fear over picking up the critters.

“The numbers of complaints, in rental buildings in particular, are continuing,” she said.